Process of preserving wood



Patented Feb. 23,192

UNITED STATES PATENT OFFICE.

RANDOLPH LEEDOM, OE CLIFTON, NEW JERSEY, AssIGNoR To THE wEsTERN UNION TELEGRAPH GOMPANY, OF NEW YORK, N. Y., A CORPORATION OF E YORK.

rRocEss or P/RESERVING woon.

\ No Drawing.

To all whom it may concern:

Be it known that I, RANDOLPH LEEDOM, a citizen of the United States, residing at Clifton, in the county of Passaic and State I of New Jersey, ,have invented certain new and useful Improvements in Processes of Preserving lVood, of which the following is a specification.

My invention relates to the preservation 10 of wood, particularly telephone and telegraph poles and the like, from the ravages of boring organisms and decay fungi which cause rapid destruction of wood, and has for its object the provision of an expedient and 1 economical method of causing a deeper and more uniform penetration of the preserving medium, such as coal or wood tar derivatives, for example, coal tar creosote, into the surface layer of the wood and into any season checks or cracks. J

Of the known methods of ap lying liquid preservatives to wood, the pro ess known as the superficial treatment, in which the preservative medium is merely applied to the wood in a hot state by means of a brush or spray, would appear as now racticed to be the most economical consi ered from a standpoint of commercial application since the large and costly installations necessary in the other knownmethods are not required in this process, but considered from the standpoint of actual results based upon a.

comparison of wood treated with preserva- P tive by this method and 4 other known methods it was found that wood impregnated with preservative by the su erficial treatment exhibited the serious draw ack or disadvantage of offering little,.if any, re-

sistance to the boring. organisms and fungi that cause wood decay, due to the slight and uneven penetration of the preserving medium into the surface of the wood and almost negligible absorption of the preservative by the cells present therein. This method offers the additional disadvantage as re ards the initial condition of the wood pr1or to its treatment with the preserving medium, in that if the wood. is green, or if the surface is wet or cold, the preservative either runs off or coagulates beforeit can enter the cells during the step of heating or drying the wood, causing this procedure to be extremely ineificacious. I have now found that by giving the wood a preliminary con- Application filed June 4,1923. Serial No. 643,427.

ditioning or charring treatment by means of heat, and then immediately applying the preservative medium while the wood surface is still hot, the difficulties above noted are obviated, and I obtain a deeper, more uniform, and more thorough surface penetra tion of the preservative medium into the wood with a resultant greater absorption of the liquid in the wood per unit area of surface treated. The charring process also opens up season checks and cracks to a degree approximating ultimate seasoning and thoroughly sterilizes the wood.

My improved process may be carried out by either bringing an intensely hot flame into intimate contact with the surface of the wood to be treated, or by allowing or directing a flame to impinge or play upon the'surface of the wood, maintaining the flame in' contact therewith until the wood becomes hot and all the moisture is driven off; at least from the surface layer, and then while the wood is stillhot applying the preservative medium, such as coal tar creosote, in a heated state either by means of a brush or a spray or other suitable method. In my preferred embodiment a flame is allowed to play upon the surface of a pole either lying on the ground or standing in a line until the desired de ee of charring has been attained, and w ile the charred leis still hot treating it with a spray of eated coal tar creosote, induced by forcing the heated liquid by means of a pump through a nozzle. The desired de ree of charring is determined, as is well namely:

the Ien h tion OF own by two factors, (1) by increasing or decreasing of the flame, and (2) by the durathe flames contact with the wood.

As a result of having the surface of the wood carrying a coating of dry char and the preserving medium being hot at the moment of application thereto, there is produced a deeper penetration of the creosote oil into the wood with an attendant greater absorption of the said liquid. Although this is my preferred manner of applying the preservative, other ways, such as by brushing, dipping, and tlie like, are applicable, and I do not desire to be limited to either one of these procedures of applying the liquid thereto, as any would suflice to attain the same result.

The conditioning or' charring treatmentexpels or liberates the water retained within the cell walls of the wood without rupturing or injurgingits cellular structure, and simultaneously causes the formation of a thin outer coating of charred wood on or about the surface of the wood treated, the depth of which being dependent upon the intensity of the flame and time of its contact with the wood. This thin outer shell being highly plprous and being in a hot dry condition at t e sprayed thereon, results in a more rapid, uniform, and deeper penetration of the preservative medium into the surface of the wood, and consequently a greater absorption of the liquid than that ordinarily obtained with the oldsuperficial treatment. The hot charred condition of the wood at the time the preservative is applied results in maintaining the preserving medium in a thoroughly fluid state for a longer period of time than if the timber .were unheated, thus deeper, penetration. The charred surface, because of its porous nature absorbs and holds the-oil, and acts as a reservoir, thus maintaining a quantity of oil adjacent'to the uncharred timber, sand allowing the penetration to continue for a long period of time. This latter action is not possible when charring is not employed as the hot oil is moment the heated preservative is causing nfi t held in contact with the pole but runs Preheating of the timber by'charring, ex-

pands the cells and the contained air to a considerable depth, and as the oilis applied 3 to produce a hot dry char and applying a hot preserving medium to said hot surface.

2. The process of preserving wood which comprises charring the surface of the wood to-produce a hot dry char and applying hot creosote to said hot surface. 5

3. The process of preserving wood which comprises charring the surface of the wood by applying a flame to produce a hot dry char and to open up season checks and cracks, and applying a preserving medium 5 to the wood while it is still hot, whereby the preserving medium will penetrate deeply into the checks and cracks.

In testimony whereof I afiix my signature.

RANDOLPH LEEDOM. 

